1. Field of the Invention
The present invention relates generally to worker-access systems and to planks used with scaffolding systems. More particularly, the present invention relates to an end cap suitable for use with planks, such as hollow core planks. In its most preferred embodiment, the present invention relates to an extruded channel end cap for covering and protecting the end of a scaffolding plank formed with a hollow core and made of a non-metallic material, such as fiberglass or other composite material, and to an arrangement for securing the end cap to the plank. The channel is designed for replaceably supporting a plurality of hooks.
2. Description of the Prior Art
A wide variety of scaffolding systems, also called worker-access systems, are known to the art. The assignee of the present invention markets such systems in the United States. The major components of its systems include tubular, horizontal plank support members arranged for a particular application and planks which are removably placed on the members to allow workers to stand in desired elevated locations at a construction, renovation or other job site. A large number of planks now employed in the United States are made from steel. They typically have an upper planar surface which may include opened or roughened areas to allow water and wind to pass therethrough and to provide a non-slip surface for worker safety. Such planks typically include depending side walls which are inwardly bent at the bottom. Hooks adapted to be removably placed over horizontal scaffolding support members are typically welded to the ends of these planks.
While such scaffolding planks have met with considerable commercial success and have been used in many thousands of locations, certain problems remain. The most important is the weight of the steel planks and another is the fact that the hooks are permanently welded or otherwise attached to the planks making repair or replacement of the hooks time consuming and expensive.
It is also well-known that "high" or "low" hooks may be employed with such planks, depending on the complexity of the scaffolding system and on whether it may be desired to have the planking arranged, without spacers, in a side-by-side arrangement. In certain systems, the high hooks are used to raise the planking level with respect to the horizontal plank support members so that they are above plank couplers. One such type of connection is shown in U.S. Pat. No. 4,586,842 issued May 6, 1986 and assigned to the assignee of the present invention. The named inventor is Joseph S. Puccinelli, and the patent is entitled "Scaffold Joint For A Scaffold Structure". The horizontal members are illustrated at 18 in the figures and planks may be supported on high hooks so that they pass over the ring connections shown at 22.
It is also known to arrange the hooks to allow the planks to be reversed, from end-to-end without interference. In other words, the opposite ends of an individual plank have the hooks arranged at different locations to facilitate reversibility. It is further known, in existing systems, to employ a hold down finger along with the hooks to prevent wobbling of the plank on the horizontal supports if a worker were to walk along an edge thereof.
Certain technology changes have occurred in recent years, especially in Europe, with regarding to scaffolding planks. One such development is described in German Patent No. DE 40 36 026 A1, a copy of which is provided with this specification, along with a non-official translation thereof. The planking system described in this patent is made from a much thinner gauge steel than that used with earlier systems. The planks are configured with a generally planar upper surface and two hollow cores extending the full length thereof. The plank surface and the cores include various corrugations to increase the strength and stiffness of the plank. Such planks provide strength capabilities similar to those of the previously described planks, at a much lower weight. Accordingly, the planks are easier to carry and to erect.
As illustrated and described hereafter, end caps with lobes are provided in certain European systems for coupling the hollow core planks to a channel shaped support system. The end cap includes a flange adapted to extend along the upper surface of the plank and a bottom flange which fits under the hollow cores. Rivets are used to affix the end cap to the plank. The end cap also includes one or more elongate lobes adapted to be received and held in an elongate channel support. Preferably, the lobe is less than one-half the width of the channel support, so that another plank may be placed in end-to-end relationship with the first plank and be supported by the same channel member.
A variety of other types of planking systems are known in the scaffold art, including planks made from plywood or other kinds of lumber. One known structure includes two steel side members which have slots into which a wood plank is placed. Extruded aluminum ends are permanently attached to the side members. The ends include spaced apart top and bottom plates and an outer edge which extends upwardly and downwardly therefrom. Hooks slide over the outer edge and are welded or otherwise secured thereto. Since the hooks extend outwardly from the outer edge of the channel member, they are located a considerable distance from the plank. During use, stresses are transferred between the side members and the horizontal supports through the hooks.
A more complete description of the prior art is set forth in the description of FIGS. 1-4 in U.S. patent application Ser. No. 08/651,202, filed May 17, 1996, which is cross-referenced above.
Several difficulties remain with current scaffolding. The non-interchangeability of hooks for a variety of different scaffold support systems is one problem, especially for scaffolding erection entities which may maintain large inventories of a variety of components. It is also cumbersome in the manufacture of scaffolding planks to use different support components for each width of plank. It is also important that stresses generated during use of scaffolding planks be distributed appropriately from the plank to the support system. Furthermore, it is important to recognize the difficulties which can be encountered in replacing bent or broken hooks.
The patent application cross-referenced above sets forth an end cap system for metallic scaffolding planks formed with hollow cores, which overcomes a number of the disadvantages of the prior art systems noted above. However, it has been found that the further improvements in the end cap system of the cross referenced patent application would be desirable when the plank, with respect to which the end cap system is used, is made from a non-metallic material, such as fiberglass, or another composite material, and formed with one or more generally hollow cores.